EP3148252B1

EP3148252B1 - Voice service switching method and device in single radio voice call continuity

Info

Publication number: EP3148252B1
Application number: EP14896691.4A
Authority: EP
Inventors: Yanglin YE; Xiaobo Wu; Weiwei CHONG; Tao Deng
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2014-06-30
Filing date: 2014-06-30
Publication date: 2018-12-12
Anticipated expiration: 2034-06-30
Also published as: CN106233781A; US20170111829A1; EP3148252A4; JP2017528092A; EP3148252A1; JP6414634B2; CN106233781B; WO2016000134A1; RU2659571C1; US10397834B2

Description

TECHNICAL FIELD

Embodiments of the present invention relate to the communications field, and more specifically, to a single radio voice call continuity handover method and apparatus.

BACKGROUND

Single radio voice call continuity (SRVCC for short) is a voice over LTE (VoLTE for short) service continuity solution proposed by the 3rd Generation Partnership Project (3GPP for short). The solution is mainly used to ensure voice service continuity when a voice service of VoLTE user equipment (UE for short) is handed over to a 2/3G circuit-switched (CS) domain.
FIG. 1A to FIG. 1C show a signaling interworking diagram of SRVCC in the prior art. As shown in FIG. 1A to FIG. 1C, in an SRVCC process, a mobile switching center (MSC for short) initiates an initial session handover process to an IP multimedia subsystem (IMS for short) (step a1), and triggers the IMS to perform session handover and remote leg update (step a2), so as to hand over a voice session to a CS domain; on an IMS side, the session handover is completed, an IMS side access leg resource is released (step a3), and a session termination message is sent to a PCRF (step a4); the PCRF sends a re-authentication request message to a gateway device (step a5), where the message is used to instruct the gateway device to delete a voice bearer (that is, a bearer whose QCI is equal to 1), and the gateway device is a gateway device that integrates a service gateway (SGW for short) and a packet data gateway (PGW); further, the gateway device sends a bearer deletion request to an MME (step a6) to request deletion of a voice service bearer. Likewise, in the SRVCC process, the VoLTE user equipment hands over an original voice service from an evolved packet system (EPS for short) network to a 2/3G network. After the handover is completed, the mobility management entity (MME for short) in the EPS network (that is, on an EPS side) sends a bearer deletion instruction message to the gateway device (step b12), where the message is used to request deletion of a bearer that is previously used for bearing a voice service, and the bearer refers to a bearer whose quality of service class identifier (QCI) is 1; after deleting a voice service bearer, the SGW/PGW initiates a bearer deletion request to the MME (step b13); after the voice service bearer is deleted, the MME sends a bearer deletion response to the SGW/PGW (step b14).
Based on the foregoing technical solution, in the SRVCC process, an original voice service bearer whose QCI is equal to 1 is deleted on both the EPS side and the IMS side. In addition, in the prior art, a time sequence for performing bearer deletion on the two sides is not defined. That is, in step a5, the gateway device receives the re-authentication request message sent by the PCRF and needs to perform an operation of deleting the voice service bearer, while in step b12, the MME sends the bearer deletion instruction message to the gateway device, and the gateway device also performs an operation of deleting the voice service bearer, which causes a conflict in the SRVCC process, and may even cause handover termination on the EPS side, and consequently the voice service is interrupted.
"3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Single Radio Voice Call Continuity (CRVSS); state 2 (Release 12)" 3GPP standard; 3GPP TS 23.216 v12.1.0, 20 June 2014 specifies the architecture enhancements for SRVCC between the following access systems for voice calls that are anchored in the IMS: from E-UTRAN to 3GPP2 1xCS; from E-UTRAN to UTRAN/GERAN; from UTRAN (HSPA) to UTRAN/GERAN; from UTRAN/GERAN to E-UTRAN; and from GERAN to UTRAN(HSPA).

SUMMARY

The invention is set out in the appended set of claims.
The embodiments and/or examples of the following description which are not covered by the appended claims are considered as not being part of the present invention.
Embodiments of the present invention provide a single radio voice call continuity handover apparatus and method, which can avoid a conflict in an SRVCC process.
According to a first aspect, a voice service handover method in single radio voice call continuity SRVCC is provided, including: recording, by a mobility management entity MME, whether a bearer deletion request message sent by a gateway device is received; and receiving, by the MME, a prompt message that is sent by a mobile switching center MSC and indicates completion of handover from packet-switched PS to circuit-switched CS, and if the MME determines that the bearer deletion request message is received, skipping sending, by the MME, a bearer deletion instruction message to the gateway device, and skipping deleting, by the MME, a local voice service bearer resource; wherein the skipping deleting, by the MME, the local voice service bearer resource comprises skipping initiating, by the MME, a bearer deletion process.
With reference to the first aspect, in a first possible implementation manner, if the MME determines that the bearer deletion request message is not received, the MME sends a access bearer release request message to the gateway device, and deletes the local voice service bearer resource.
With reference to the first aspect, in a second possible implementation manner, before the recording, by an MME, whether a bearer deletion request message sent by a gateway device is received, the method includes: receiving, by the MME, the bearer deletion request message sent by the gateway device; and the method further includes: sending, by the MME, a bearer deletion response message to the gateway device, and skipping deleting the local voice service bearer resource.
According to a second aspect, a voice service handover apparatus in single radio voice call continuity SRVCC is provided, including: a processing module, configured to record whether a bearer deletion request message sent by a gateway device is received; and a receiving module, configured to receive a prompt message that is sent by a mobile switching center MSC and indicates completion of handover from packet-switched PS to circuit-switched CS; where the processing module is configured to: after the receiving module receives the prompt message that is sent by the mobile switching center MSC and indicates the completion of the handover from packet-switched PS to circuit-switched CS, if determining that the bearer deletion request message is received by the apparatus, skip sending a bearer deletion instruction message to the gateway device, and skip deleting a local voice service bearer resource; wherein the skipping deleting the local voice service bearer resource comprises skipping initiating a bearer deletion process.
With reference to the second aspect, in a first possible implementation manner, the processing module is further configured to: if determining that the bearer deletion request message is not received by the apparatus, skip sending an access bearer release request message to the gateway device, and skip deleting the local voice service bearer resource is not deleted.
With reference to the secondaspect, in a second possible implementation manner, the receiving module is further configured to receive the bearer deletion request message sent by the gateway device; and the processing module is further configured to: send a bearer deletion response message to the gateway device, and skip deleting the local voice bearer resource.
Based on the single radio voice call continuity handover method and apparatus provided in the embodiments of the present invention, an MME records whether a bearer deletion request message sent by a gateway device is received; and if the MME determines that the bearer deletion request message is received, the MME does not send a bearer deletion instruction message to the gateway device, and does not delete a local voice service bearer resource. Therefore, after the MME performs voice service bearer deletion on an IMS side, the MME does not perform voice service bearer deletion on an EPS side, thereby avoiding a conflict in an SRVCC process.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A to FIG. 1C show a signaling interworking diagram of an SRVCC process in the prior art;
FIG. 2 shows a schematic flowchart of a single radio voice call continuity handover method according to an embodiment of the present invention;
FIG. 3A to FIG. 3C show a signaling interworking diagram of a single radio voice call continuity handover method according to an embodiment of the present invention;
FIG. 4 shows a schematic flowchart of a single radio voice call continuity handover method according to an example;
FIG. 5A to FIG. 5C show a signaling interworking diagram of a single radio voice call continuity handover method according to an example;
FIG. 6 shows a schematic flowchart of a single radio voice call continuity handover method according to another example;
FIG. 7A to FIG. 7C show a signaling interworking diagram of a single radio voice call continuity handover method according to another example;
FIG. 8 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an embodiment of the present invention;
FIG. 9 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an example;
FIG. 10 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to another example;
FIG. 11 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an embodiment of the present invention;
FIG. 12 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an example; and
FIG. 13 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to another example .

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
FIG. 2 shows a schematic flowchart of a single radio voice call continuity handover method according to an embodiment of the present invention. The method may be executed by any proper apparatus, for example, executed by an MME. However, the present invention is not limited thereto. As shown in FIG. 2, the method includes:
S201. An MME records whether a bearer deletion request message sent by a gateway device is received.
For example, the gateway device may be a gateway device that integrates an SGW and a PGW.
In an SRVCC process, a main process on an IMS side includes: an IMS completes session handover, releases an IMS side access leg resource, and sends a session termination message to a PCRF; the PCRF sends a re-authentication request message to the gateway device, where the message is used to instruct the gateway device to delete a voice bearer; further, the gateway device sends a bearer deletion request to the MME. In this case, the MME locally records a state indicating whether the bearer deletion request message is received, and sets an initial state: if the bearer deletion request message is not received, the initial state is recorded as false; or if the bearer deletion request message is received by the MME, the MME records the state as true. This embodiment of the present invention imposes no limitation on setting of the state.
The IMS in this embodiment of the present invention is a standard next-generation network architecture for a telecommunications operator who intends to provide mobile and fixed multimedia services. It uses VoIP execution that is executed based on SIP and 3GPP, and runs over the standard Internet Protocol. The IMS can support existing phone systems (both packet-switched and circuit-switched).
S202. The MME receives a prompt message indicating completion of handover from packet-switched PS to circuit-switched CS; and if the MME determines that the bearer deletion request message is received, the MME does not send a bearer deletion instruction message to the gateway device, and does not delete a local voice service bearer resource.
In the SRVCC process, the MME in an EPS network receives the prompt message indicating the completion of the handover from packet-switched PS to circuit-switched CS, and determines, according to whether the bearer deletion request message is received, whether to send the bearer deletion instruction message to the gateway device and delete the local voice service bearer resource.
According to the state set in S201, when the state is recorded as true, the MME does not send the bearer deletion instruction message to the gateway device, and does not deletes the local voice service bearer resource. In this way, after receiving the bearer deletion request message sent by the gateway device, the MME deletes the voice service bearer resource, and the MME does not send the bearer deletion instruction message to the gateway device afterwards, thereby avoiding a conflict in an SRVCC process.
Optionally, if the MME determines that the bearer deletion request message is not received, the MME sends the bearer deletion instruction message to the gateway device. That is, the MME receives the PS to CS handover completion prompt message, and when the state in the MME is recorded as false, the MME sends the bearer deletion instruction message to the gateway device. Therefore, the MME determines that the bearer deletion request message sent by the gateway device is not received, and sends the bearer deletion instruction message to the gateway device, thereby avoiding a conflict in the SRVCC process.
Optionally, the method further includes: receiving, by the MME, the bearer deletion request message sent by the gateway device; sending, by the MME, a bearer deletion response message to the gateway device, and skipping deleting the local voice service bearer resource. In a scenario in which the MME receives the bearer deletion request message sent by the gateway device, the MME records that the bearer deletion request message sent by the gateway device is received, and the MME sends the bearer deletion response message to the gateway device, and does not delete the local voice service bearer resource.
Therefore, based on the technical solution provided in this embodiment of the present invention, after receiving a prompt message indicating completion of handover from packet-switched PS to circuit-switched CS, an MME determines, according to whether a bearer deletion request message sent by a gateway device is received by the MME, whether to send a bearer deletion instruction message to the gateway device. In this way, after the MME performs voice service bearer deletion on an IMS side, no voice service bearer deletion process is performed on an EPS side, thereby avoiding a conflict in an SRVCC process.
FIG. 3A to FIG. 3C show a signaling interworking diagram of a single radio voice call continuity handover method according to an embodiment of the present invention. The method may be executed by any proper apparatus, for example, executed by an MME. However, the present invention is not limited thereto. This embodiment of the present invention is a specific implementation manner of the embodiment of the present invention shown in FIG. 2.
In this embodiment of the present invention and another embodiment of the present invention, in an SRVCC handover process, an IMS side process includes a series of processes that are triggered after an MSC sends an initial session handover message to an IMS, an EPS side process includes a series of processes that are triggered after the MSC sends a PS to CS handover response message to an MME. The IMS side process and the EPS side process are independent of each other.
As shown in FIG. 3A to FIG. 3C, this embodiment of the present invention includes:
In an SRVCC process, an IMS side process includes:

a301. An MSC sends an initial session handover message to an IMS.
a302. The IMS performs session handover and remote leg update.
a303. The IMS releases an IMS access leg.
a304. The IMS sends a session termination request message to a PCRF.
a305. The PCRF sends a re-authentication request message to a gateway device.

The PCRF sends the re-authentication request message to the gateway device, where the message is used to instruct the gateway device to delete a voice bearer.
a306. The gateway device sends a bearer deletion request message to an MME.
After deleting a voice bearer resource, the gateway device sends the bearer deletion request message to the MME, so as to request the MME to delete a voice service bearer.
a307. The MME records whether the bearer deletion request message sent by the gateway device is received.
Specifically, for example, if the bearer deletion request message is received by the MME, the MME records an initial state as true; or if the bearer deletion request message is not received by the MME, the MME records the initial state as false.
For example in a306, the bearer deletion request message sent by the gateway device is received by the MME; in this case, the MME records the state as true, and does not delete a local voice service bearer.
a308. The MME sends a bearer deletion response message to the gateway device.
In the SRVCC process, an EPS network side process includes:

b301. The MSC sends a PS to CS handover response message to the MME.
b302. The MME sends a handover instruction message to an eNB.
b303. The eNB sends a mobility from E-UTRAN command to UE.
b304. An RRC connection is established between the UE and an RNC.
b305. The RNC performs reconfiguration discovery.
b306. Reconfiguration between the RNC and the MSC is completed.
b307. The MSC sends, to the MME, a PS to CS handover completion prompt message.
b308. The MME determines that the bearer deletion request message sent by the gateway device is received, and the MME does not send a bearer deletion instruction message to the gateway device, and does not delete a local voice service bearer resource. by now, the MME does not send the bearer deletion instruction message to the gateway device, and does not initiate a bearer deletion process, the EPS network side process ends, and no subsequent processing process is performed.

Specifically, for example, in a306, the bearer deletion request message sent by the gateway device is received by the MME; in this case, the MME determines, according to a previous record, that the bearer deletion request message sent by the gateway device is received, and the MME does not send the bearer deletion instruction message to the gateway device, and does not delete the local voice service bearer resource.
In this way, the MME records that the bearer deletion request message sent by the gateway device is received; after receiving the PS to CS handover completion prompt message, the MME determines that the bearer deletion request message sent by the gateway device is received, and does not initiate the bearer deletion process, thereby avoiding a process conflict caused by repeated deletions of the voice bearer resource in the SRVCC process.
In another scenario of this embodiment of the present invention, that is, in the IMS side process of the SRVCC process, if the bearer deletion request message sent by the gateway device is not received by the MME, b308 and subsequent steps in the EPS side process are:

b308. The MME determines that the bearer deletion request message sent by the gateway device is not received.
b309. The MME sends a PS to CS handover completion answer message to the MSC.
b310. The MME sends an access bearer release request message to the gateway device.
b311. The gateway device sends an access bearer release response message to the MME.
b312. The MME sends a bearer context release request message to the eNB.
b313. The MME sends the bearer deletion instruction message to the gateway device.
The bearer deletion instruction message is used to instruct the gateway device to delete the voice service bearer resource.
b314. The gateway device sends a credit control update request message to the PCRF.

The credit control update request message is used to notify the PCRF that the gateway device needs to delete the voice service bearer.
b315. The PCRF sends a credit control update answer message to the gateway device.
The PCRF sends the credit control update answer message to the gateway device, and agrees with the gateway device to delete the voice service bearer.
b316. The gateway device sends a bearer deletion request message to the MME.
The gateway device deletes a local voice service bearer, and sends the bearer deletion request message to the MME, to request the MME to delete the voice service bearer resource.
b317. The MME sends a bearer deletion response message to the gateway device.
After deleting the local voice service bearer resource, the MME sends the bearer deletion response message to the gateway device. On the foregoing basis that the bearer deletion request message is not received by the foregoing MME, no process conflict occurs when the MME deletes the local voice service bearer resource herein.
b318. The PCRF sends a session interrupt request message to the IMS.
The session interrupt request message is used to notify the IMS device of the SRVCC handover completion.
For example, after receiving the credit control update request message sent by the gateway device in b314, the PCRF sends the session interrupt request message to the IMS.
There is no sequence between b318 to b319 and b316 to b317.
b319. The IMS sends a session interrupt answer message to the PCRF.
After receiving the session interrupt request message, the IMS performs voice service bearer resource deletion.
After the IMS receives the session interrupt request message sent by the PCRF, the foregoing operations in a304 to a308 are not performed.
b320. Perform an optional PS process.
Therefore, based on the technical solution provided in this embodiment of the present invention, after receiving a prompt message indicating completion of handover from packet-switched PS to circuit-switched CS, an MME determines, according to a record that a bearer deletion request message sent by a gateway device is received by the MME, not to send a bearer deletion instruction message to the gateway device. In this way, after the MME performs voice service bearer deletion on an IMS side, no voice service bearer deletion process is performed on an EPS side, thereby avoiding a conflict in an SRVCC process.
FIG. 4 shows a schematic flowchart of a single radio voice call continuity handover method according to an example. The method may be executed by any proper apparatus, for example, executed by a PCRF. As shown in FIG. 4, the method includes:

S401. A policy and charging rules function PCRF unit receives a session termination request message sent by an IP multimedia subsystem IMS, where the session termination request message includes an information element used to indicate a reason for session termination, where the reason for session termination is on-hook or SRVCC handover completion.
S402. If the reason for session termination is SRVCC handover completion, the PCRF does not send a re-authentication request message to a gateway device.

Optionally, if the reason for session termination is on-hook, the PCRF sends a re-authentication request message to the gateway device.
Based on the technical solution provided in this example, when an SRVCC handover process is performed, on the basis that a received session termination request message includes an information element used to indicate a reason for session termination, if a PCRF determines that the reason for session termination is SRVCC handover, the PCRF does not send a re-authentication request message to a gateway device. That is, no voice service bearer deletion process is performed on an IMS side, thereby avoiding a process conflict in SRVCC handover.
FIG. 5A to FIG. 5C show a signaling interworking diagram of a single radio voice call continuity handover method according to an example. The method may be executed by any proper apparatus, for example, executed by a PCRF. This example is a specific implementation method of the example shown in FIG. 4.
As shown in FIG. 5A to FIG. 5C, this example includes:
In an SRVCC process, an IMS side process includes:

a501 to a503: refer to a301 to a303 in FIG. 3A to FIG. 3C.
a504. An IMS sends a session termination request message to a PCRF.

This step specifically includes: the IMS sends the session termination request message to the PCRF, where the session termination request message includes an information element used to indicate a reason for session termination, where the reason for session termination is on-hook or SRVCC handover completion. If the PCRF determines that the reason for session termination is on-hook, the PCRF sends a re-authentication request message to a gateway device. If the PCRF determines that the reason for session termination is SRVCC handover completion, no re-authentication request message is sent to the gateway device, that is, no voice bearer deletion process is initiated, and no subsequent process is performed.
In the SRVCC process, an EPS network side process includes:

b501 to b507: refer to b301 to b307 in FIG. 3A to FIG. 3C; and b508 to b511: refer to b309 to b312 in FIG. 3A to FIG. 3C.
b512. An MME sends a bearer deletion instruction message to a gateway device.
b513. The gateway device sends a credit control update request message to the PCRF.

The credit control update request message is used to notify the PCRF that the gateway device needs to delete a voice service bearer.
b514. The PCRF sends a credit control update answer message to the gateway device.
The PCRF sends the credit control update answer message to the gateway device, and agrees with the gateway device to delete the voice service bearer.
b515. The gateway device sends a bearer deletion request message to the MME.
The gateway device deletes a local voice service bearer, and sends the bearer deletion request message to the MME, to request the MME to delete a voice service bearer resource.
b516. The MME sends a bearer deletion response message to the gateway device.
After deleting a local voice service bearer resource, the MME sends the bearer deletion response message to the gateway device.
In this way, when the PCRF determines that the reason for session termination is SRVCC handover completion, no re-authentication request message is sent to the gateway device, that is, no voice bearer deletion process is performed. That is, in the SRVCC process, no voice bearer deletion process is initiated on the IMS side, and the MME initiates the voice bearer deletion process only on the EPS side, thereby avoiding a process conflict in SRVCC handover.
b517. The PCRF sends a session interrupt request message to the IMS.
For example, after receiving the credit control update request message sent by the gateway device in b513, the PCRF sends the session interrupt request message to the IMS.
There is no sequence between b517 to b518 and b515 to b516.
b518. The IMS sends a session interrupt answer message to the PCRF.
b519. Perform an optional PS process.
Therefore, based on the technical solution provided in this example, an IMS sends a session termination request message to a PCRF, where the session termination request message includes an information element used to indicate that a reason for session termination is on-hook or SRVCC handover completion. If the PCRF determines that the reason for session termination is on-hook, the PCRF sends a re-authentication request message to a gateway device. If the PCRF determines that the reason for session termination request is SRVCC handover completion, no re-authentication request message is sent to the gateway device, that is, no voice bearer deletion process is initiated. In this way, a process conflict is avoided when a voice service bearer deletion process is initiated on both an IMS side and an EPS side in an SRVCC process.
In another scenario of this example, if the PCRF determines that the reason for session termination is on-hook, the PCRF sends a re-authentication request message to the gateway device, that is:
a505. The PCRF sends the re-authentication request message to the gateway device.
The PCRF receives the session termination request message sent by the IMS, if the session termination request message includes the information element used to indicate that the reason for session termination is on-hook, the PCRF returns a session termination answer message to the IMS, and sends the re-authentication request message to the gateway device.
a506. The gateway device sends the bearer deletion request message to the MME.
After receiving the re-authentication request message sent by the PCRF, the gateway device sends a re-authentication answer to the PCRF, and sends the bearer deletion request message to the MME.
a507. The MME sends the bearer deletion response message to the gateway device.
In this case, the EPS network side process includes:

b501 to b507: refer to b301 to b307 in FIG. 3A to FIG. 3C; and b508 to b511: refer to b309 to b312 in FIG. 3A to FIG. 3C.
b512. The MME sends a bearer deletion instruction message to the gateway device.
b513. The gateway device sends a credit control update request message to the PCRF.

The credit control update request message is used to notify the PCRF that the gateway device needs to delete a voice service bearer.
b514. The PCRF sends a credit control update answer message to the gateway device.
The PCRF sends the credit control update answer message to the gateway device, and agrees with the gateway device to delete the voice service bearer.
b515. The gateway device sends a bearer deletion request message to the MME.
The gateway device deletes a local voice service bearer, and sends the bearer deletion request message to the MME, to request the MME to delete a voice service bearer resource.
b516. The MME sends a bearer deletion response message to the gateway device.
After deleting a local voice service bearer resource, the MME sends the bearer deletion response message to the gateway device. Because the reason for session termination is on-hook instead of an SRVCC process conflict, and user equipment is in an on-hook state, producing no adverse effect such as handover interruption.
b517. The PCRF sends a session interrupt request message to the IMS.
b518. The IMS sends a session interrupt answer message to the PCRF.
b519. Perform an optional PS process.
Therefore, based on the technical solution provided in this example, an IMS sends a session termination request message to a PCRF, if the session termination request message includes an information element used to indicate a reason for session termination is on-hook, the PCRF sends a re-authentication request message to a gateway device. If the PCRF determines that the reason for session termination request is SRVCC handover completion, no re-authentication request message is sent to the gateway device, that is, no voice bearer deletion process is initiated. In this way, a process conflict is avoided when a voice service bearer deletion process is initiated on both an IMS side and an EPS side in an SRVCC process.
FIG. 6 shows a schematic flowchart of a single radio voice call continuity handover method according to an example. The method may be executed by any proper apparatus, for example, executed by an IMS.
As shown in FIG. 6, the method includes:
S601. After receiving an initial session handover message sent by a mobile switching center MSC and completing session handover and remote leg update, an IP multimedia subsystem IMS starts a delay timer.
Specifically, in common SRVCC handover, the delay timer is configured on an SCC application server (Service Centralization and Continuity Application Server, "SCC AS" for short) in the IMS; or in emergency call SRVCC handover, the delay timer is configured on an emergency access transfer function (EATF for short) unit in the IMS.
A delay time set on the delay timer is 8 seconds It is recommended in a protocol that an SRVCC process needs to be completed within 300 ms. Considering that a delay of message retransmission in an abnormal scenario is 7 seconds, it is recommended that a delay time set on the delay timer is 8 seconds.
S602. Before a delay time on the delay timer expires, the IMS receives a session interrupt request message sent by a policy and charging rules function PCRF unit, and the IMS releases an IMS access leg.
That is, before the delay time on the delay timer expires, in an SRVCC handover process, an EPS side handover process is completed. After the IMS receives the session interrupt request message sent by the PCRF unit and releases the IMS access leg, an SRVCC process on an IMS side is completed.
Therefore, based on the technical solution provided in this example, in an SRVCC process, on an IMS side, an IMS starts a delay timer before releasing an IMS access leg; during a delay process according to the delay timer, a voice service bearer deletion process is performed on an EPS side; before a delay time set on the delay timer expires, the IMS receives a session interrupt request message sent by a policy and charging rules function PCRF unit, releases the IMS access leg, and does not perform the voice service bearer deletion process. Therefore, in the SRVCC handover process, the voice service bearer deletion process is performed only on the EPS side, thereby avoiding a process conflict in SRVCC handover.
FIG. 7A to FIG. 7C show a signaling interworking diagram of a single radio voice call continuity handover method according to an example. This example is a specific implementation manner of the example shown in FIG. 6.
As shown in FIG. 7A to FIG. 7C, this example includes:

a701. An MSC sends an initial session handover message to an IMS.
a702. The IMS performs session handover and remote leg update.
a703. The IMS starts a delay timer.

On the basis that in common SRVCC handover and emergency SRVCC handover, logical network elements initiating session release in the IMS are different, in the common SRVCC handover, the delay timer is configured on an SCC AS in the IMS; in the emergency SRVCC handover, the delay timer is configured on an EATF in the IMS. A delay time set on the delay timer may be 8 seconds.
a704. The IMS releases an IMS access leg.
Before the delay time on the delay timer expires, the IMS receives a session interrupt request message sent by a policy and charging rules function PCRF unit, releases the IMS access leg, and performs voice service bearer resource deletion.
By now, an IMS side process in an SRVCC process is completed, that is, the IMS does not send a session termination message to a gateway device, and does not initiate a voice service bearer deletion process.
In the SRVCC process, an EPS network side process includes:

b701 to b707: refer to b301 to b307; and b708 to b711: refer to b309 to b312 in FIG. 3A to FIG. 3C.
b712. An MME sends a bearer deletion instruction message to a gateway device.
b713. The gateway device sends a credit control update request message to a PCRF.

The credit control update request message is used to notify the PCRF that the gateway device needs to delete a voice service bearer.
b714. The PCRF sends a credit control update answer message to the gateway device.
The PCRF sends the credit control update answer message to the gateway device, and agrees with the gateway device to delete the voice service bearer.
b715. The gateway device sends a bearer deletion request message to the MME.
The gateway device deletes a local voice service bearer, and sends the bearer deletion request message to the MME, to request the MME to delete a voice service bearer resource.
b716. The MME sends a bearer deletion response message to the gateway device.
After deleting a local voice service bearer resource, the MME sends the bearer deletion response message to the gateway device. In this way, after the IMS starts the delay timer, during a delay process according to the delay timer, the voice service bearer deletion process is performed on the EPS side, and before the delay time set on the delay timer expires, the IMS receives the session interrupt request message sent by the policy and charging rules function PCRF unit, releases the IMS access leg, and does not perform the voice service bearer deletion process.
b717. The PCRF sends a session interrupt request message to the IMS.
Before the delay time on the delay timer expires, the PCRF sends the session interrupt request message to the IMS, where the message is used to notify the IMS device that SRVCC handover is completed.
For example, after the gateway device sends the credit control update request message to the PCRF in b713, the PCRF sends the session interrupt request message to the IMS.
There is no sequence between b717 to b718 and b715 to b716.
b718. The IMS sends a session interrupt answer message to the PCRF.
After receiving the session interrupt request message, the IMS performs voice service bearer resource deletion.
b719. Perform an optional PS process.
Therefore, based on the technical solution provided in this example, in an SRVCC process, on an IMS side, an IMS starts a delay timer before releasing an IMS access leg, and during a delay process according to the delay timer, a voice service bearer deletion process is performed on an EPS side; before a delay time set on the delay timer expires, the IMS receives a session interrupt request message sent by a PCRF and releases the IMS access leg, and no voice service bearer deletion process is initiated on an IMS side afterwards. Therefore, in an SRVCC handover process, the voice service bearer deletion process is performed only on the EPS side, thereby avoiding a process conflict in SRVCC handover.
FIG. 8 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an embodiment of the present invention. The method may be executed by any proper apparatus, for example, executed by an MME; however, the present invention is not limited thereto. The apparatus provided in this embodiment of the present invention may execute the methods provided in the embodiments of the present invention shown in FIG. 2 and FIG. 3A to FIG. 3C.
As shown in FIG. 8, the apparatus includes: a processing module 801 and a receiving module 802.
The processing module 801 is configured to record whether a bearer deletion request message sent by a gateway device is received.
In an SRVCC process, a main process on an IMS side includes: an IMS completes session handover, releases an IMS side access leg resource, and sends a session termination message to a PCRF; the PCRF sends a re-authentication request message to the gateway device, where the message is used to instruct the gateway device to delete a voice bearer; further, the gateway device sends a bearer deletion request to the MME. In this case, the MME locally records a state indicating whether the bearer deletion request message is received, and sets an initial state: if the bearer deletion request message is not received, the initial state is recorded as false; or if the bearer deletion request message is received by the MME, the MME records the state as true. This embodiment of the present invention imposes no limitation on setting of the state.
The receiving module 802 is configured to receive a prompt message that is sent by a mobile switching center MSC and indicates completion of handover from packet-switched PS to circuit-switched CS.
The processing module 801 is further configured to: after the receiving module receives the prompt message that is sent by the mobile switching center MSC and indicates the completion of the handover from packet-switched PS to circuit-switched CS, if determining that the bearer deletion request message is received by the apparatus, skip sending a bearer deletion instruction message to the gateway device, and skip deleting a local voice service bearer resource.
For example, after the receiving module receives the prompt message that is sent by the mobile switching center MSC and indicates the completion of the handover from packet-switched PS to circuit-switched CS, if determining that the bearer deletion request message is received by the apparatus, the processing module 801 does not instruct a sending module in the apparatus to send the bearer deletion instruction message to the gateway device.
In the SRVCC process, the MME in an EPS network receives the prompt message indicating the completion of the handover from packet-switched PS to circuit-switched CS, and determines, according to whether the bearer deletion request message is received, whether to send the bearer deletion instruction message to the gateway device and delete the local voice service bearer resource. When the state is recorded as true, the MME does not send the bearer deletion instruction message to the gateway device, and deletes the local voice service bearer resource. In this way, after receiving the bearer deletion request message sent by the gateway device, the MME deletes a voice service bearer resource, and the MME does not send the bearer deletion instruction message to the gateway device afterwards, thereby avoiding a conflict in an SRVCC process.
In another embodiment of the present invention, the receiving module 802 is further configured to receive the bearer deletion request message sent by the gateway device; the processing module 801 is further configured to: send a bearer deletion response message to the gateway device, and skip deleting the local voice bearer resource.
For example, if the receiving module 802 is further configured to receive the bearer deletion request message sent by the gateway device, the processing module 801 instructs the sending module in the apparatus to send the bearer deletion response message to the gateway device.
That is, in a scenario in which the MME receives the bearer deletion request message sent by the gateway device, the MME records that the bearer deletion request message sent by the gateway device is received, and the MME sends the bearer deletion response message to the gateway device, and does not delete the local voice service bearer resource.
Optionally, in another embodiment of the present invention, the processing module 801 is further configured to: if determining that the bearer deletion request message is not received by the apparatus, skip sending an access bearer release request message to the gateway device, and skip deleting the local voice service bearer resource.
Therefore, based on the apparatus provided in this embodiment of the present invention, after receiving a prompt message indicating completion of handover from packet-switched PS to circuit-switched CS, an MME determines, according to whether a bearer deletion request message sent by a gateway device is received by the MME, whether to send a bearer deletion instruction message to the gateway device. In this way, after the MME performs voice service bearer deletion on an IMS side, no voice service bearer deletion process is performed on an EPS side, thereby avoiding a conflict in an SRVCC process.
The single radio voice call continuity handover apparatus in this embodiment of the present invention shown in FIG. 8 may correspond to the single radio voice call continuity handover methods provided in the embodiments of the present invention, and operations and/or functions of the modules of the apparatus provided in this embodiment of the present invention are separately used to implement corresponding processes of the methods in FIG. 2 to FIG. 7A to FIG. 7C. For brevity, details are not described herein again.
FIG. 9 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an example. The method may be executed by any proper apparatus, for example, executed by a PCRF. The apparatus provided in this example may execute the methods provided in the example shown in FIG. 4 and FIG. 5A to FIG. 5C.
As shown in FIG. 9, the apparatus includes:

a receiving module 901, configured to receive a session termination request message sent by an IP multimedia subsystem IMS, where the session termination request message includes an information element used to indicate that a reason for session termination is on-hook or SRVCC handover completion; and
a processing module 902, configured to: if determining that the reason for session termination is SRVCC handover completion, skip sending a re-authentication request message to a gateway device.

For example, the processing module 902 determines that the reason for session termination is SRVCC handover completion, and does not instruct a sending module to send the re-authentication request message to the gateway device.
Optionally, in another example, the processing module 902 is further configured to: if determining that the reason for session termination is on-hook, send the re-authentication request message to the gateway device. For example, if the processing module 902 determines that the reason for session termination is on-hook, the sending module is instructed to send the re-authentication request message to the gateway device.
Based on the apparatus provided in this example, when an SRVCC handover process is performed, on the basis that a received session termination request message includes an information element used to indicate a reason for session termination, if a PCRF determines that the reason for session termination is SRVCC handover, the PCRF does not send a re-authentication request message to a gateway device. That is, no voice service bearer deletion process is performed on an IMS side, thereby avoiding a process conflict in SRVCC handover.
The single radio voice call continuity handover apparatus in this example shown in FIG. 9 may correspond to the single radio voice call continuity handover methods provided in the example, and operations and/or functions of the modules of the apparatus provided in this example are separately used to implement corresponding processes of the methods in FIG. 2 to FIG. 7A to FIG. 7C. For brevity, details are not described herein again.
FIG. 10 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an example. The method may be executed by any proper apparatus, for example, executed by an IMS. The apparatus provided in this example may execute the methods provided in the example in FIG. 6 and FIG. 7A to FIG. 7C.
As shown in FIG. 10, the apparatus includes:

a receiving module 1001, configured to receive an initial session handover message sent by a mobile switching center MSC; and
a processing module 1002, configured to: after the initial session handover message is received, perform session handover and remote leg update, and start a delay timer.

Specifically, in common SRVCC handover, the delay timer is configured on an SCC application server SCC AS of the apparatus; or
in emergency SRVCC handover, the delay timer is configured on an emergency access transfer function EATF unit of the apparatus.
A delay time on the delay timer is greater than or equal to 8 seconds.
The receiving module 1001 is further configured to: before the delay time on the delay timer expires, receive a session interrupt request message sent by a policy and charging rules function PCRF unit; and
the processing module 1002 is further configured to: after the session interrupt request message is received, release an IMS access leg.
Therefore, based on the apparatus provided in this example, in an SRVCC process, on an IMS side, an IMS starts a delay timer before releasing an IMS access leg; during a delay process according to the delay timer, a voice service bearer deletion process is performed on an EPS side; before a delay time set on the delay timer expires, the IMS receives a session interrupt request message sent by a policy and charging rules function PCRF unit, releases the IMS access leg, and does not perform the voice service bearer deletion process. Therefore, in the SRVCC handover process, the voice service bearer deletion process is performed only on the EPS side, thereby avoiding a process conflict in SRVCC handover.
The single radio voice call continuity handover apparatus in this example shown in FIG. 10 may correspond to the single radio voice call continuity handover methods provided in the example and operations and/or functions of the modules of the apparatus provided in this example are separately used to implement corresponding processes of the methods in FIG. 2 to FIG. 7A to FIG. 7C. For brevity, details are not described herein again.
FIG. 11 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an embodiment of the present invention. The method may be executed by any proper apparatus, for example, executed by an MME; however, the present invention is not limited thereto. The apparatus provided in this embodiment of the present invention may execute the methods provided in the embodiments of the present invention shown in FIG. 2 and FIG. 3A to FIG. 3C.
As shown in FIG. 11, the apparatus includes: a processor 1101 and a receiver 1102.
The processor 1101 is configured to record whether a bearer deletion request message sent by a gateway device is received.
In an SRVCC process, a main process on an IMS side includes: an IMS completes session handover, releases an IMS side access leg resource, and sends a session termination message to a PCRF; the PCRF sends a re-authentication request message to the gateway device, where the message is used to instruct the gateway device to delete a voice bearer; further, the gateway device sends a bearer deletion request to the MME. In this case, the MME locally records a state indicating whether the bearer deletion request message is received, and sets an initial state: if the bearer deletion request message is not received, the initial state is recorded as false; or if the bearer deletion request message is received by the MME, the MME records the state as true. This embodiment of the present invention imposes no limitation on setting of the state.
The receiver 1102 is configured to receive a prompt message that is sent by a mobile switching center MSC and indicates completion of handover from packet-switched PS to circuit-switched CS.
The processor 1101 is further configured to: after the receiving module receives the prompt message that is sent by the mobile switching center MSC and indicates the completion of the handover from packet-switched PS to circuit-switched CS, if determining that the bearer deletion request message is received by the apparatus, skip sending a bearer deletion instruction message to the gateway device, and skip deleting a local voice service bearer resource.
For example, after the receiving module receives the prompt message that is sent by the mobile switching center MSC and indicates the completion of the handover from packet-switched PS to circuit-switched CS, if determining that the bearer deletion request message is received by the apparatus, the processor 1101 does not instruct a sending module in the apparatus to send the bearer deletion instruction message to the gateway device.
In the SRVCC process, the MME in an EPS network receives the prompt message indicating the completion of the handover from packet-switched PS to circuit-switched CS, and determines, according to whether the bearer deletion request message is received, whether to send the bearer deletion instruction message to the gateway device and delete the local voice service bearer resource. When the state is recorded as true, the MME does not send the bearer deletion instruction message to the gateway device, and deletes the local voice service bearer resource. In this way, after receiving the bearer deletion request message sent by the gateway device, the MME deletes a voice service bearer resource, and the MME does not send the bearer deletion instruction message to the gateway device afterwards, thereby avoiding a conflict in an SRVCC process.
In another embodiment of the present invention, the receiver 1102 is further configured to receive the bearer deletion request message sent by the gateway device; the processor 1101 is further configured to: send a bearer deletion response message to the gateway device, and skip deleting the local voice bearer resource.
Optionally, in another embodiment of the present invention, the processor 1101 is further configured to: if determining that the bearer deletion request message is not received by the apparatus, skip sending an access bearer release request message to the gateway device, and skip deleting the local voice service bearer resource.
For example, if the receiver 1102 is further configured to receive the bearer deletion request message sent by the gateway device, the processor 1101 instructs the sending module in the apparatus to send the bearer deletion response message to the gateway device.
Therefore, based on the apparatus provided in this embodiment of the present invention, after receiving a prompt message indicating completion of handover from packet-switched PS to circuit-switched CS, an MME determines, according to whether a bearer deletion request message sent by a gateway device is received by the MME, whether to send a bearer deletion instruction message to the gateway device. In this way, after the MME performs voice service bearer deletion on an IMS side, no voice service bearer deletion process is performed on an EPS side, thereby avoiding a conflict in an SRVCC process.
The single radio voice call continuity handover apparatus in this embodiment of the present invention shown in FIG. 11 may correspond to the single radio voice call continuity handover methods provided in the embodiments of the present invention, and operations and/or functions of the modules of the apparatus provided in this embodiment of the present invention are separately used to implement corresponding processes of the methods in FIG. 2 to FIG. 7A to FIG. 7C. For brevity, details are not described herein again.
It should be understood that in this embodiment of the present invention, the processor may be a central processing unit (CPU for short), or the processor may be another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or another programmable logic device, a discrete gate or a transistor logic device, a discrete hardware assembly, or the like. The general purpose processor may be a microprocessor, or the processor may also be any conventional processor, or the like.
In an implementation process, the foregoing steps may be completed by using an integrated logic circuit of hardware in the processor or an instruction in a form of software. The steps of the methods disclosed with reference to the embodiments of the present invention may be directly performed by a hardware processor, or may be performed by using a combination of hardware in the processor and a software module. The software module may be located in a mature storage medium in the field, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically-erasable programmable memory, a register. The storage medium is located in the memory, and the processor reads information in the memory and completes the steps of the foregoing methods in combination with the hardware of the processor. To avoid repetition, details are not described herein.
FIG. 12 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an example. The method may be executed by any proper apparatus, for example, executed by a PCRF. The apparatus provided in this example may execute the methods provided in the example shown in FIG. 4 and FIG. 5A to FIG. 5C.
As shown in FIG. 12, the apparatus includes:

a receiver 1201, configured to receive a session termination request message sent by an IP multimedia subsystem IMS, where the session termination request message includes an information element used to indicate that a reason for session termination is on-hook or SRVCC handover completion; and
a processor 1202, configured to: if determining that the reason for session termination is SRVCC handover completion, skip sending a re-authentication request message to a gateway device.

For example, the processor 1202 determines that the reason for session termination is SRVCC handover completion, and does not instruct a sending module to send the re-authentication request message to the gateway device.
Optionally, in another example, the processor 1202 is further configured to: if determining that the reason for session termination is on-hook, send the re-authentication request message to the gateway device. For example, if the processor 1202 determines that the reason for session termination is on-hook, the sending module is instructed to send the re-authentication request message to the gateway device.
Based on the apparatus provided in this example, when an SRVCC handover process is performed, on the basis that a received session termination request message includes an information element used to indicate a reason for session termination, if a PCRF determines that the reason for session termination is SRVCC handover, the PCRF does not send a re-authentication request message to a gateway device. That is, no voice service bearer deletion process is performed on an IMS side, thereby avoiding a process conflict in SRVCC handover.
The single radio voice call continuity handover apparatus in this example shown in FIG. 12 may correspond to the single radio voice call continuity handover methods provided in the example, and operations and/or functions of the modules of the apparatus provided in this example are separately used to implement corresponding processes of the methods in FIG. 2 to FIG. 7A to FIG. 7C. For brevity, details are not described herein again.
In an implementation process, the foregoing steps may be completed by using an integrated logic circuit of hardware in the processor or an instruction in a form of software. The steps of the methods disclosed with reference to the example may be directly performed by a hardware processor, or may be performed by using a combination of hardware in the processor and a software module. The software module may be located in a mature storage medium in the field, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically-erasable programmable memory, a register. The storage medium is located in the memory, and the processor reads information in the memory and completes the steps of the foregoing methods in combination with the hardware of the processor. To avoid repetition, details are not described herein.
FIG. 13 shows a schematic block diagram of a single radio voice call continuity handover apparatus according to an example. The method may be executed by any proper apparatus, for example, executed by an IMS. The apparatus provided in this example may execute the methods provided in the example shown in FIG. 6 and FIG. 7A to FIG. 7C.
As shown in FIG. 13, the apparatus includes:

a receiver 1301, configured to receive an initial session handover message sent by a mobile switching center MSC; and
a processor 1302, configured to: after the initial session handover message is received, perform session handover and remote leg update, and start a delay timer.

Specifically, in common SRVCC handover, the delay timer is configured on an SCC application server SCC AS of the apparatus; or
in emergency SRVCC handover, the delay timer is configured on an emergency access transfer function EATF unit of the apparatus.
A delay time on the delay timer is greater than or equal to 8 seconds.
The receiver 1301 is further configured to: before the delay time on the delay timer expires, receive a session interrupt request message sent by a policy and charging rules function PCRF unit; and
the processor 1302 is further configured to: after the session interrupt request message is received, release an IMS access leg.
Therefore, based on the apparatus provided in this example, in an SRVCC process, on an IMS side, an IMS starts a delay timer before releasing an IMS access leg; during a delay process according to the delay timer, a voice service bearer deletion process is performed on an EPS side; before a delay time set on the delay timer expires, the IMS receives a session interrupt request message sent by a policy and charging rules function PCRF unit, releases the IMS access leg, and does not perform the voice service bearer deletion process. Therefore, in the SRVCC handover process, the voice service bearer deletion process is performed only on the EPS side, thereby avoiding a process conflict in SRVCC handover.
The single radio voice call continuity handover apparatus in this example shown in FIG. 13 may correspond to the single radio voice call continuity handover methods provided in the example, and operations and/or functions of the modules of the apparatus provided in this example are separately used to implement corresponding processes of the methods in FIG. 2 to FIG. 7A to FIG. 7C. For brevity, details are not described herein again.
It should be understood that in this example, the processor may be a central processing unit (CPU for short), or the processor may be another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or another programmable logic device, a discrete gate or a transistor logic device, a discrete hardware assembly, or the like. The general purpose processor may be a microprocessor, or the processor may also be any conventional processor, or the like.
In an implementation process, the foregoing steps may be completed by using an integrated logic circuit of hardware in the processor or an instruction in a form of software. The steps of the methods disclosed with reference to the example may be directly performed by a hardware processor, or may be performed by using a combination of hardware in the processor and a software module. The software module may be located in a mature storage medium in the field, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically-erasable programmable memory, a register. The storage medium is located in the memory, and the processor reads information in the memory and completes the steps of the foregoing methods in combination with the hardware of the processor. To avoid repetition, details are not described herein.
A person of ordinary skill in the art may be aware that, in combination with the examples described in the embodiments disclosed in this specification, method steps and units may be implemented by electronic hardware, computer software, or a combination thereof. To clearly describe the interchangeability between the hardware and the software, the foregoing has generally described steps and compositions of each embodiment according to functions. Whether the functions are performed by hardware or software depends on particular applications and design constraint conditions of the technical solutions. A person of ordinary skill in the art may use different methods to implement the described functions for each particular application, but it should not be considered that the implementation goes beyond the scope of the present invention.
It may be clearly understood by a person skilled in the art that, for the purpose of convenient and brief description, for a detailed working process of the foregoing system, apparatus, and unit, reference may be made to a corresponding process in the foregoing method embodiments, and details are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described apparatus embodiment is merely exemplary. For example, the unit division is merely logical function division and may be other division in actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces. The indirect couplings or the communication connections between the apparatuses may also be implemented in electronic, mechanical, or other forms.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. A part or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments of the present invention.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in a form of hardware, or may be implemented in a form of a software functional unit.
When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of the present invention essentially, or the part contributing to the prior art, or all or a part of the technical solutions may be implemented in the form of a software product. The software product is stored in a storage medium and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or a part of the steps of the methods described in the embodiments of the present invention. The foregoing storage medium includes: any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM for short), a random access memory (RAM for short), a magnetic disk, or an optical disc.
The foregoing descriptions are merely specific embodiments of the present invention, but are not intended to limit the protection scope of the present invention. Any modification or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

A voice service handover method in single radio voice call continuity, SRVCC, comprising:
recording (201, a307), by a mobility management entity, MME, whether a bearer deletion request message for deleting a voice service bearer resource, sent by a gateway device is received; and

receiving (202, b307), by the MME, a prompt message that is sent by a mobile switching center, MSC, and indicates completion of handover from packet-switched, PS, to circuit-switched, CS, and

characterized in that the method further comprises:
if the MME determines that the bearer deletion request message has been received, skipping sending (b308), by the MME, a bearer deletion instruction message to the gateway device, and skipping deleting, by the MME, the voice service bearer resource; wherein the skipping deleting, by the MME, the voice service bearer resource comprises skipping initiating, by the MME, a bearer deletion process.
The method according to claim 1, wherein the method further comprises:
if the MME determines that the bearer deletion request message is not received, sending (b313), by the MME, a access bearer release request message to the gateway device, and deleting, by the MME, the voice service bearer resource.
The method according to claim 1, wherein before the recording (201, a307), by an MME, whether a bearer deletion request message sent by a gateway device is received, the method comprises: receiving (a306), by the MME, the bearer deletion request message sent by the gateway device;
and the method further comprises:
sending (a308), by the MME, a bearer deletion response message to the gateway device, and skipping deleting the voice service bearer resource.
The method according to claim 1, wherein the recording, by a mobility management entity, MME, whether a bearer deletion request message sent by a gateway device is received comprises:
if the bearer deletion request message is received by the MME, the MME records an initial state as true; or

if the bearer deletion request message is not received by the MME, the MME records the initial state as false.
The method according to claim 4, wherein if the MME determines that the bearer deletion request message is received, skipping sending, by the MME, a bearer deletion instruction message to the gateway device, and skipping deleting the voice service bearer resource comprises:
when the initial state is recorded as true, the MME does not send the bearer deletion instruction message to the gateway device, and does not delete the voice service bearer resource.
A mobility management entity, MME, in single radio voice call continuity, SRVCC, comprising:
a processing module (801), configured to record whether a bearer deletion request message for deleting a voice service bearer resource, sent by a gateway device is received; and

a receiving module (802), configured to receive a prompt message that is sent by a mobile switching center, MSC, and indicates completion of handover from packet-switched, PS, to circuit-switched, CS; wherein

characterized in that
the processing module (801) is further configured to: after the receiving module (802) receives the prompt message that is sent by the MSC and indicates the completion of the handover from PS to CS, if determining that the bearer deletion request message has been received by the MME, skip sending a bearer deletion instruction message to the gateway device, and skip deleting the voice service bearer resource;

wherein the skipping deleting the voice service bearer resource comprises skipping initiating a bearer deletion process.
The MME according to claim 6, wherein the processing module (801) is further configured to: if determining that the bearer deletion request message is not received, skip sending an access bearer release request message to the gateway device, and skip deleting the voice service bearer resource.
The MME according to claim 6, wherein the receiving module (802) is further configured to receive the bearer deletion request message sent by the gateway device; and the processing module (801) is further configured to: send a bearer deletion response message to the gateway device, and skip deleting the voice bearer resource.
The MME according to claim 6, wherein the processing module (801) is configured to:
if the bearer deletion request message is received, recording an initial state as true; or

if the bearer deletion request message is not received, recording the initial state as false.
The MME according to claim 9, wherein the processing module (801) is configured to:
when the initial state is recorded as true, do not send the bearer deletion instruction message to the gateway device, and do not delete the voice service bearer resource.